1. Field of the Invention
The present invention relates to a semiconductor device and a process for production of the same, more particularly relates to a thin package semiconductor device and a process of production of the same.
2. Description of the Related Art
The most flexible type of thin package semiconductor device mounting a semiconductor chip (LSI or other semiconductor chip) for the increase of pins, reduction of the pitch between connection terminals, and reduction of thickness and size of the device as a whole is the tape carrier package (TCP).
A TCP is produced by mounting a semiconductor chip on an insulating tape substrate (usually a resin film) by tape automated bonding (TAB). Typically, first, a copper foil is attached to a resin film provided with a predetermined pattern of openings, then the copper foil is etched to pattern it to form predetermined copper leads. Next, a semiconductor chip is positioned and held within an opening of the resin film, a plurality of connection terminals of the chip (in general gold bumps) and a corresponding plurality of copper leads on the resin film are bonded together, then the semiconductor chip and part of the copper leads are sealed by a resin to complete a single semiconductor package unit. This operation is repeated for every opening while intermittently feeding the resin film, whereby a large number of semiconductor package units are formed on a single film. Finally, the large number of semiconductor package units formed along the longitudinal direction of the film are cut and separated from each other so as to obtain individual semiconductor packages.
FIG. 1 is a perspective view of a semiconductor device of the related art obtained by connecting a semiconductor chip and TCP leads. It shows the state before the individual TCPs are cut from the tape. The TCP 10 uses a resin film (for example, a polyimide resin film) 1 as a substrate and has leads 2 formed by etching of a copper foil on top. Further, sprocket holes 3 are formed at the two side edges of the resin film 1 for feeding the film. An opening 5 for accommodating a semiconductor chip 4 (in general called a xe2x80x9cdevice holexe2x80x9d) and window holes 9 are also formed in the center of the resin film 1 as illustrated.
The state of connection of the semiconductor chip and the leads of the package is shown in the sectional view of FIG. 2, which shows the center portion of the semiconductor device of FIG. 1 enlarged. A semiconductor chip 4 is positioned and placed in the device hole 5 of the resin film 1, then the front ends of the leads 2 are bonded on the bumps on the electrodes (normally projections formed by gold plating). The leads are normally bonded all together using a special bonding tool. Note that to assist the bonding of the bumps 6 with the front ends of the leads 2 comprised of copper, the bumps are gold plated in advance before the bonding step. Finally, while not shown in FIG. 1, the semiconductor chip 4 and the leads 6 are protected from the humidity, contamination, etc. of the ambient environment by sealing the two to cover them by a resin 7. As the sealing resin 7, use is made for example of an epoxy resin.
The above semiconductor device of the related art however suffered from the following problems (a) to (e):
(a) There are limits to the reduction of the mounting height of the semiconductor chip on a resin film, so there are limits to the reduction of thickness of the semiconductor device. That is, the semiconductor device is fixed by thin copper leads projecting out in a bridge like manner into the opening of the resin film, so securing sufficient mounting strength requires that the copper leads, the resin film serving as the support member, and the device as a whole be at least a certain thickness. If reinforcing the strength by the resin sealed portion, a broad area has to be sealed thickly. It is difficult however to secure complete sealing across a broad area. Further, thick sealing runs counter to the desire to reduce thickness.
(b) Semiconductor chips become brittle and easily warpable when made thin enough for reducing the thickness of the semiconductor device. Each requires a special carrier. Handling is extremely complicated and a large number of steps are required. Further, improvement of the manufacturing yield also becomes difficult.
(c) The individual semiconductor chips have to be individually positioned and bonded in the openings of the resin film, so production of a large number of semiconductor packages requires a long, complicated production process.
(d) In the case of a stacked chip type semiconductor device obtained by stacking semiconductor chips in a plurality of layers, each individual semiconductor chip has to be positioned and bonded in the opening of the resin film, so the production process becomes even longer and more complicated.
(e) Not only is there a manufacturing variation in the thickness of the chips, but there is also variation in the individual mounting heights. As a result, a variation in height arises in the semiconductor devices. It is consequently difficult to conduct electrical tests in a block before cutting and separating the film into the semiconductor package units.
An object of the present invention is to solve the above problems in the related art and provide a semiconductor device, in particular a thin semiconductor package, which reduces and simultaneously achieves a uniform mounting height, does not require complicated steps for mounting individual chips, improves the manufacturing yield, achieves a uniform height of the semiconductor device without being affected by the variation in thickness of the chips, and enables execution of electrical tests in a block and a process for production of the same.
To achieve the above object, according to a first aspect of the present invention, there is provided a semiconductor device, wherein a semiconductor chip is housed with its active surface facing upward in a through hole of a printed circuit board provided with an interconnection pattern on its top surface, electrode terminals of the active surface are connected with the interconnection pattern by bonding wires, a sealing resin layer seals the bonding wires and semiconductor chip integrally and fixes the semiconductor chip in the through hole, and a bottom surface of the printed circuit board, a downward facing back surface of the semiconductor chip, and a bottom surface of the sealing resin layer are finished to the same flat surface by grinding.
According to a second aspect of the present invention, there is provided a process of production of a semiconductor device comprising bonding a temporary support to a bottom surface of a printed circuit board provided with a through hole and an interconnection pattern on its top surface to define a bottom of the through hole, bonding a semiconductor chip with its back surface facing downward to the bottom, connecting electrode terminals of the upward facing active surface of the semiconductor chip and the interconnection pattern by bonding wires, using a sealing resin layer to integrally seal the bonding wires and the semiconductor chip and fix the semiconductor chip in the through hole, removing the temporary support, and finishing a bottom surface of the printed circuit board, a downward facing back surface of the semiconductor chip, and a bottom surface of the sealing resin layer to the same flat surface by grinding.
Preferably, the printed circuit board has a large number of areas for forming semiconductor devices, all of the steps are performed for each of the areas so as to form a large number of semiconductor devices on the printed circuit board in a block, then the printed circuit board is cut between the individual areas to separate the individual semiconductor devices.
According to a third aspect of the present invention, there is provided a semiconductor device, wherein a semiconductor chip is housed with its active surface facing upward in a through hole of a lead frame having leads, electrode terminals of the active surface are connected with the top surface of the leads by bonding wires, a sealing resin layer seals the bonding wires and semiconductor chip integrally and fixes the semiconductor chip in the through hole, and a bottom surface of the lead frame, a downward facing back surface of the semiconductor chip, and a bottom surface of the sealing resin layer are finished to the same flat surface by grinding.
According to a fourth aspect of the present invention, there is provided a process of production of a semiconductor device comprising forming a lead frame having a planar part having leads and a vessel for housing a semiconductor chip, the bottom of the vessel projecting downward from a bottom surface of the planar part, and a top end of the vessel being open and connecting with the planar part; bonding a semiconductor chip on the bottom surface in the vessel so that its active surface faces upward and becomes higher than the bottom surface of the planar part; connecting electrode terminals of the active surface and the upper surfaces of the leads of the lead frame by bonding wires; using a sealing resin layer to integrally seal the bonding wires and the semiconductor chip and fix the semiconductor chip in the vessel; and grinding the vessel of the lead frame, the semiconductor chip, and the sealing resin layer from the bottom to substantially remove the vessel of the lead frame and finish a bottom surface of the planar part of the lead frame, a downward facing back surface of the semiconductor chip, and a bottom surface of the sealing resin layer to the same flat surface.
Preferably, the lead frame has a large number of areas for forming semiconductor devices, all of the steps are performed for each of the areas so as to form a large number of semiconductor devices on the lead frame in a block, then the lead frame is cut between the individual areas to separate the individual semiconductor devices.
According to a fifth aspect of the present invention, there is provided a semiconductor device, wherein an active surface of a semiconductor chip is bonded to a printed circuit board provided with a through hole and an interconnection pattern on its top surface, the active surface defining a bottom of the through hole; electrode terminals of the active surface defining the bottom are connected with the interconnection pattern by bonding wires passing through the through hole; a sealing resin layer fills the through hole and seals the bonding wires; and a downward facing back surface of the semiconductor chip is finished by grinding.
According to a sixth aspect of the present invention, there is provided a process of production of a semiconductor device comprising forming a printed circuit board provided with a through hole and an interconnection pattern on its top surface, bonding an active surface of a semiconductor chip to a bottom surface of the printed circuit board to define a bottom of the through hole, connecting electrode terminals of the active surface defining the bottom and the interconnection pattern by bonding wires passing through the through hole, using a sealing resin layer to fill the through hole and seal the bonding wires, and finishing a downward facing back surface of the semiconductor chip to a flat surface by grinding.
Preferably, the printed circuit board has a large number of areas for forming semiconductor devices, all of the steps are performed for each of the areas so as to form a large number of semiconductor devices on the printed circuit board in a block, then the printed circuit board is cut between the individual areas to separate the individual semiconductor devices.
According to a seventh aspect of the present invention, there is provided a semiconductor device wherein a semiconductor chip with its active surface facing downward is connected by flip chip bonding to a top surface of a printed circuit board provided with a top surface having pads connected to an interconnection pattern of its bottom surface, an underfill material covers the side faces of the semiconductor chip and fills a clearance between the active surface of the semiconductor chip and the top surface of the printed circuit board, and an upward facing back surface of the semiconductor chip is finished to a flat surface by grinding.
According to an eighth aspect of the present invention, there is provided a process of production of a semiconductor device comprising forming a printed circuit board provided with a top surface having pads connected to an interconnection pattern of its bottom surface, connecting to the top surface of the printed circuit board a semiconductor chip with its active surface facing downward by flip chip bonding, using an underfill material to cover the side faces of the semiconductor chip and fill a clearance between the active surface of the semiconductor chip and the top surface of the printed circuit board, and finishing an upward facing back surface of the semiconductor chip to a flat surface by grinding.
Preferably, the printed circuit board has a large number of areas for forming semiconductor devices, all of the steps are performed for each of the areas so as to form a large number of semiconductor devices on the printed circuit board in a block, then the printed circuit board is cut between the individual areas to separate the individual semiconductor devices.
According to a ninth aspect of the present invention, there is provided a stacked chip type semiconductor device comprised of a semiconductor chip finished by grinding of the semiconductor device as set forth in any one of the first, third, fifth, and seventh aspects of the invention another semiconductor chip bonded at its back surface to the former""s back surface.
According to a 10th aspect of the present invention, there is provided a process of production of a stacked chip type semiconductor device comprising performing all of the steps set forth in any one of the second, fourth, sixth, and eighth aspects of the invention, then bonding a back surface of another semiconductor chip to the back surface of the semiconductor chip finished by grinding.
According to an 11th aspect of the present invention, there is provided a process of production of a stacked chip type semiconductor device comprising performing all of the steps set forth in any one of the second, fourth, sixth, and eighth aspects of the invention, at each of a large number of areas for forming semiconductor devices of a printed circuit board or lead frame so as to form a large number of semiconductor devices on the printed circuit board or lead frame in a block, bonding back surfaces of other semiconductor chips to the back surfaces of the semiconductor chips finished by grinding of the semiconductor devices, then cutting the printed circuit board or lead frame between the individual areas to separate the individual semiconductor devices.